1. Field of the Invention
This invention generally relates to electro-coagulation of tissue in the body in combination with other forms of therapy using catheters.
2. Description of Related Art
It is very important to minimize the time required to stop internal bleeding in a patient. A physician has several medical instruments in his or her armamentarium for stopping such internal bleeding. In accordance with one modality that is particularly suited for bleeding into the gastrointestinal tract, a physician initially positions a flexible endoscope in the patient with its distal end proximate a hemorrhaging vessel. The physician may insert an irrigator through a working channel in the endoscope to clear the area by administering saline solution as a precursor to any attempts to stop bleeding. If the instrument being used for irrigation is like the Gold Probe.TM. hemostat manufactured by Boston Scientific Corporation, the assignee of this invention, the physician may then cauterize the bleeding vessel using a distally positioned hemostat. Such instruments are constructed to be employed through a working channel of an endoscope to seal potential bleeding sites as in the gastrointestinal tract or the esophagus. Other hemostats use mono-electropolar electrodes in which one electrode is carried by a catheter to a site while the other electrode is an exterior ground plate placed in a patient. Alternatively the physician may retract the irrigating catheter and insert an elongated needle through the endoscope to inject a vaso-constrictor into the vessel to slow hemorrhaging. Then the physician could remove the elongated needle and reinsert the hemostat to finish the operation.
The above-mentioned Gold Probe.TM. hemostat is an example of a device that supplies a suitable current density and wave form of radiofrequency energy to perform electro-coagulation or cauterization. It utilizes a catheter with a bipolar electrode assembly located on a distal flexible tip formed of a ceramic cylinder having a hemispherical end. The ceramic tip includes a pair of spaced gold spiral electrodes applied to its cylindrical surface and domed end. RF energy applied to the electrodes produces a current through adjacent tissue that heats and cauterizes the hemorrhaging vessel which is contacted by the tip of the catheter.
Notwithstanding the fact that both hemostasis and injection needle therapy are usually done on an emergency basis, the exchange of catheters to provide different functions continues and increases the risk to the patient because the time to complete therapy is extended. Extending the time to complete the therapy also increases patient discomfort. Consequently, physicians have to weigh the time, complexity and benefits of interchanging single or dual purpose catheters to change treatment modalities against whatever disadvantage may result by working with a single modality and single catheter.
Co-pending application Ser. No. 08/038,903 that is incorporated herein by reference provides a catheter generally characterized by an axially displaceable probe that acts as one of two electrodes for performing hemostatic therapy. The other electrode is spaced proximally from and is insulated with respect to the probe. The catheter has a lumen for administering irrigating fluids to tissue at the hemorrhaging vessel. In some embodiments irrigation fluid passes between the main probe and a structure at the distal end of the catheter. In other applications the distal tip portion includes separate passages for allowing an irrigating solution to pass into the area of the hemorrhaging vessel. In still another embodiment the irrigation fluid passes directly through the probe that comprises a hollow needle that also acts as an electrode and as an injection needle for administering a vasoconstrictor or other therapeutic agent into a bleeding vessel.
This apparatus, therefore, in its various embodiments, enables a physician to irrigate tissue and to treat a hemorrhaging vessel with injection therapy or hemostatic therapy without removing the catheter apparatus from the working channel or lumen of an endoscope. However, many physicians are familiar with standard devices such as the Gold Probe hemostat. One particular embodiment of Ser. No. 08/038,903, that is applied to a Gold Probe hemostat discloses a probe tip with two separate electrodes and an extensible conductive probe that provides a physician alternatives for hemostatic therapy. In accordance with one option the probe tip electrodes constitute bipolar electrodes and the extensible conductive probe is inactive electrically. In accordance with the other option the extensible probe is active and one or both of the probe tip electrodes act as a second electrode. This approach can complicate the apparatus required for connecting an RF generator source to the electrodes and related circuitry and can also increase the burden on the physician using the apparatus. Moreover, such procedures differ from those familiar to the physician as a result of use of prior art devices, so such a catheter assembly can impose other complications.